Heat detection unit

ABSTRACT

A heat detection unit including in a sealed block a contact assembly connected to an electric driving circuit for fire alarm or extinguisher apparatus and adapted to be closed by selfturning or deforming action of an associated heat-sensitive bimetal element. The bimetal element is arranged to be thermally close contact with a sealing metal cap of the block having a heat-collecting plate member provided with a plurality of holes adapted to have circumferential heat collected at both surfaces of the plate and transmitted to the cap through the shortest distance.

United States Patent [54] HEAT DETECTION UNIT 3 Claims, 9 Drawing Figs.

[52] US. Cl 337/380, 236/101, 337/377 [51 1 Int. Cl H011! 37/04, HOlh37/52 [50] Field of Search 236/101;

[56] References Cited UNITED STATES PATENTS 3,297,845 1/1967 Mertler337/380 X 3,227,845 1/1966 Barz 337/354 2,667,553 1/1954 Moorhead et al337/365 1,832,761 11/1931 Brady 337/380 Primary Examiner-Bernard A.Gilheany Assistant Examiner-Dewitt M. Morgan ArmrneyWolfe, Hubbard, Voit& Osann ABSTRACT: A heat detection unit including in a sealed block acontact assembly connected to an electric driving circuit for fire alarmor extinguisher apparatus and adapted to beclosed by self-turning ordeforming action of an associated heat-sensitive bimetal element. Thebimetal element is arranged to be thermally close contact with a sealingmetal cap of the block having a heat-collecting plate member providedwith a plurality of holes adapted to have circumferential heat collectedat both surfaces of the plate and transmitted to the cap through theshortest distance.

,1 Ba l BATENTED En 41911 sum 10F 3 lOo INVENTOR HIROAKI MAMIYAATTORNEYS PATENIEU 5914 l97| SHEET 3 0F 3 INVENTOR HIROAKI MAMIYAATTORNEYS HEAT DETECTION UNIT This invention relates in general toextraordinary heat or fire detection unit adapted to close contacts inelectric circuit for driving fire alarm devices, fire extinguishingdevices or the like devices upon detecting a state of fire occurrence orimmediate before such occurrence.

More specifically, it relates to a heat detection unit provided with aheat collector element which is capable of having the highest heatreceptivity in spite of its occupying smallest heat-receivingsurfacearea.

For the heat detection unit of the type as referred to, there have beensuggested various types of unit including, for example, a type in whichsuch heat-sensitive element as a bimetal, thermistor or the like is madeto be enclosed in a porous guard member, and a type in which similarheat-sensitive element is held in a metal case of a high thermalconductivity so as to be brought into close contact with the latter.

However, such conventional types of heat detection unit have beeninherently involving several defects. In the case of the first one ofthe two types as referred to in the above, the guard member enclosingthe heat-sensitive element is not effective in thermal function at alland even obstructs the passage of heated air currents to theheat-sensitive element due to its insufficient ventilation. In addition,since normally the heat-receptive surface area of the heat-sensitiveelement has been remarkably small, the unit of this type has been faultyin that the same could have been only raised to required orpredetermined operating temperature finally at the time when the firehas reached a certain large scale.

In the case of the second type of the conventional unit as referred toin the above, while effective heat-receiving surface area could beenlarged by means of the metal case as compared with that of the firstone of the types, the heat-sensitive element has not been placed inposition for direct contact with the heated air current and, thus, theheat receptivity of the element has been forced to be deteriorated. If ametal case of larger dimension would be utilized in this second type ofthe unit for the purpose of compensating the above fault, such a largerdimension would result only in a useless increase in the thermalcapacity of the unit so that the fire could grow to a large scale beforethe air temperature inside the metal case would be raised to thepredetermined temperature level at which the heat-sensitive elementcould be actuated.

A principal object of the present invention is, therefore, to provide aheat detection unit in which the heat-sensitive element can be raised inan extremely short time period while the same occupies an extremelysmall space.

A further object of the present invention is to provide a heat detectionunit which is constructed in such manner that the heat received atrespective parts of the unit will be efiectively converged into theheat-sensitive element so as not to be dispersed to other parts.

Other objects and advantages of the invention will become clear uponreading the following disclosures set forth with reference to theaccompanying drawings, in which:

FIG. I is a front side plan view of the heat detection unit according tothe present invention.

FIG. 2 is a vertically sectioned view taken along a line II-II in FIG.I.

FIG. 3 is a reverse side plan view of the unit shown in FIG. 1.

FIG. 4 is a detailed vertical section of main part of the unit of FIG.1, shown in an enlarged scale and, specifically, taken along a lineIV-IV in FIG. 5.

FIG. 5 is a perspective view of the main part shown in FIG. 4 asdisassembled.

FIG. 6A is a perspective view of a heat-collecting member of the presentinvention, which is shown here fragmentarily.

FIG. 6B is a vertical sectioned view of the heat-collecting member alongVl--VI line in FIG. 6A.

FIG. 7 is a perspective view of another embodiment of theheat-collecting member.

FIG. 8 is an enlarged fragmentary perspective of the heatcollectingmember of FIG. 7.

Referring now to FIGS. 1 and 2, the heat detection unit comprises ingeneral a sealed block A containing the heat-sensitive element therein,a heat collector rim or plate H mounted around said block A forcollecting and transferring the heat of circumferential air to the blockA, and a base member B to which the block A is secured. The unit will benormally fixed to ceiling surface of a room at the part of said basemember B.

The heat-sensitive element employed in the unit according to the presentinvention comprises a discor saucer-shaped bimetal l, which is, as willbe best seen in FIGS. 4 and 5, placed inside a space a of the sealedblock A formed with a receptacle 2 made of a synthetic resin and a metalcap 4, in such manner that peripheral edge of the bimetal 1 will beengaged in respective steps 3a, 3b and 3c of supporting columns 311, 3band 3c projected along peripheral edge of the receptacle 2. Said sealedblock A is performed by squeezing end edge of the metal cap 4 into aperipheral groove 2a provided on reverse side of the receptacle 2. Thesaucer-shaped bimetal 1 is so arranged as to contact with inner surfaceof the metal cap 4 at its convex side in the normal or fixedtemperature.

In the space a of the above mentioned sealed block A, there is furthercontained a contact assembly S in addition to the disk-shaped bimetalalso in the sealed state. Said contact assembly S comprises a movablecontact 5 secured on a movable contact arm 6 and a fixed contact 7. Saidcontact arm 6 is in turn secured at an end to an extending end of arod-shaped lead 8 inserted through a small hole 8a made in thereceptacle 2, so as to oppose toconcave side at the time of the fixedtemperature of the bimetal 1. At the center of the movable contact arm6, thereis provided an actuating button 6a, which is broughtsubstantially into the disk-shaped bimetal I so that self-turningmovement of the bimetal l at the time when the same detects an excessheat over the fixed temperature will be transmitted to the arm 6. Thefixed contact 7 is provided at a position opposed to said movablecontact 5 as spaced by a proper distance, and is fixed to an end ofanother rod-shape lead 9 inserted through a small hole 9a made in thereceptacle 2.

The sealed block A containing the disk-shaped bimetal and the contactassembly S is held by the base member B which will be set forth indetail in the following.

Referring again to FIGS. 1 and 2 and to FIG. 3, the base member B isprovided with mounting holes 10a and 10b for mounting the unit toceiling surface, and is formed as a whole in a streamline shapeprojecting downwardly, so that heated air current will be smoothly ledalong the base member surface toward the sealed block A containing theheat sensor bimetal 1. At the mounting side of the base member B to theceiling, there is provided a hollow room 11, in which terminal plates13a and 13b separated by separating walls 12 are fixed to the base B bymeans of self-tapping screws, and wire fastening screws 13a and 13b arescrewed to the terminal plates 13a and 13b, respectively. Adjacent tosaid terminal plates 13a and 13b, holes 15a and 15b are provided in suchmanner that they will be aligned with holes 17a and 17b respectivelymade through each of two projections 16a and 16b projecting out of thebase B, so as to be a pair of continuous holes 15a-l7 a and I5b-l7b,through which said leads 8 and 9 are inserted, respectively. Upper endsof these leads 8 and 9 are fixed to a part of the terminal plates 13aand 13 b by means of soldering, respectively. Therefore, the sealedblock A referred to in the above will be fixed to the base member B bymeans of the leads 8 and 9. The base member B is further provided, inaddition to the above mentioned projections 16a and 16b, with ribs 18aand 18b likely projected out of the base member B in downward direction.These ribs and 18b are formed for the purpose of protecting the heatcollector H, which will now be explained in the following.

The heat collector H is a member to be brought into close contactthermally with the sealed block A for the purpose of transmitting thegenerated heat rapidly from circumferential air to the bimetal 1contained in the sealed block A.

For this purpose, the heat collector H is formed in a disc shape and isprovided at its central part a cylindrical portion 19 having a height hand formed in a squeezing process, as shown in FlG. 6A. inner diameterof the cylindrical portion 19 is made to substantially coincide withoutside diameter of the sealed block A, so that the heat collector H ismounted around the sealed block A with the cylindrical'portion 19 asengaged at outside periphery of the block A and adhered thereto by meansof a proper bonding agent, thereby the collector H and block A will bemechanically and thermally bound together.

Along outer periphery of the heat collector H, there is provided a raiserib formed by a squeezing process for increasing mechanical strength ofthe collector H.

The heat collector H according to the present invention is furtherprovided with a plurality of bridge portions 21 respectively separatedat longitudinal sides from each other by a plurality of clearances orslits made radially on the disk. Such clearances will be established,for example by depressing every one of adjacent two of the bridgeportions 21, as shown in FIGS. 6A and 6B, so that the portions 21 willbe alternately stepped from adjacent ones and, thus, a plurality ofclearances t in vertical direction sufficient for passing air currenttherethrough will be provided between each of the adjacent steppedbridge portions 21.

Since the heat detection unit according to the present invention isformed in such structure as above with such components as detailed inthe above, when any fire occurs or any extraordinary temperature risewhich will cause such fire to occur is present nearby the position atwhich the heat detection unit is installed, possible heated air currentdue to the above will go up toward the unit so as to have the bimetalpiece 1 in the unit heated through the metal cap 4 and, thus,

urged to be bent upward. When the curvature of the saucertype bimetal lis thus turned upward with its own snap action due to the heat, themovable contact arm 6 will be pushed up through the actuating button 6a,so that the movable contact 5 and fixed contact 7 are closed. By thisclosing of the both contacts, the terminal plates 13a and 13b arebrought into shortcircuited condition so as to close an electric drivingcircuit for an associated alarm device or fire extinguishing system.

As will be readily appreciated from the foregoing, the feature of thepresent invention resides in that the highest heat receptivity will beobtained at the heat collector means with the smallest surface area, andthat the above-mentioned structure of the unit of the present inventionis greatly contributing to such feature due to the following phenomenonscaused by the particular structure.

That is, since the heat-collecting plate H according to the presentinvention is provided with a plurality of radial bridge portions 21respectively separated by a vertical clearance I from each other asalternately stepped or depressed, the heated air current coming up willnot only flow into reverse side of the heat collecting plate H throughthe clearances of l, but also will collide with the respective bridgeportions 21 so as to cause a turbulent or eddy current of the heated airto be generated over the entire surface area at both surfaces of theplate H, so that all of the bridge portions 21 and, consequently, thewhole of the heat-collecting plate will be highly and effectively heatedfrom its both of front and reverse sides.

Further, as the lower or front surface of the heat-collecting plate H ismade to be on a different level from that of lower surface of the metalcap 4 of the block A by a height of h, i.e., by the height correspondingto that of the cylindrical portion 19 of the plate H, theheat-collecting surface area of the unit according to the presentinvention is enlarged by an area obtained by multiplying the height hwith circumferential length of the cylindrical portion 19.

The heat of collector H thus heated up to a higher temperature will thenbe converged to the metal cap 4, which is kept at a lower temperaturethan the collector H because it is relatively hard to be heatedcomparing with the collector H. There fore, the temperature ofsaucer-shape bimetal l which is arranged thermally integral with themetal cap 4 will be quickly raised to a degree substantially identicalto the temperature of the heat collector H.

'In the above case, it will be appreciate that the particulararrangement of the respective bridge portions 21 formed radially so asto be directed to the center of the circular disc plate H will beeffective in transmitting the heat collected by the plate H to the metalcap 4 through the shortest distance and, also, in making the temperaturerise of the saucer-shaped bimetal l to be much faster. Further, theradially extending bridge portions 21 are also making theheat-collecting plate H to be stronger against any external force givenin horizontal direction.

Further in the present invention, it will be seen that the saucer-shapebimetal l is supported only by the supporting columns 3a, 3b and 3c,except the metal cap 4 covering the same. This fact is specificallyeffective in preventing the heat transmitted to the bimetal 1 from theheatcollecting plate H through the cap 4 from being dispersed to otherparts of lower temperature and consequently the temperature rise in thebimetal 1 will be effectively made to be quicker.

It will be understood that, in carrying out the present invention, thebridge portions 21 of the heat collecting plate H should not necessarilybe formed in radial arrangement or in stepped relation to each adjacentones. It will be possible to have the hot air current led to both of thefront and reverse sides of plate H simply by providing many holes orslots in the plate H as, for example, shown in FIG. 7 so as to be ableto make the heat receptivity much higher than in the case ofconventional types of the unit. It should be also understood that theeffects are obtained by so forming the heat collector as to be stepped,for example, at every two adjacent portions as shown in FIG. 8, insteadof being stepped at every one alternately.

What I claim is:

l. A heat detection comprising a sealed block including aheat-conductive metal cap, a base member for holding said sealed block,a heat-sensitive bimetal element contained in said sealed block in suchmanner that its convex side surface at lower temperature will bethermally related to said metal cap of the sealed block, a contactassembly having a movable contact and a fixed contact and contained inthe sealed block together with said bimetal element, said contactassembly being positioned adjacent said bimetal element so as to beoperated upon self-deformation of the bimetal in response to presentedheat thereto, and a heat-collecting plate member of a heat-conductivematerial brought into thermally close contact with the metal cap ofsealed block, said heat-collecting plate member being formed in adisk-shape and provided with r a plurality of bridge portionsrespectively separated from each other by a plurality of vertical slitswith respect to the plane of the disk so as to he stepped alternately,so that heat-collecting surface area of the plate member will beincreased and the plate will be heated from its both front and reversesides simultaneously. V

2. The heat detection unitas set forth in claim 1, wherein said sealedblock comprises said metal cap and an insulative receptacle memberhaving a plurality of supporting columns, and said bimetal element isheld between said columns and metal cap, thereby possible dispersion ofcollected heat from the bimetal element will be restricted to beminimum.

3. A heat detection unit comprising a sealed block including aheatconductive metal cap, a base member for holding said sealed block, aheat-sensitive bimetal element contained in said sealed block in suchmanner that its convex side surface at lower temperatures will bethermally related to said metal cap of the sealed block, a contactassembly having a movable contact and a fixed contact and contained inthe sealed block together with said bimetal element, said contactassembly being positioned adjacent said bimetal element so as to beoperated upon self-deformation of the bimetal in response to presentedheat thereto, and a heat-collecting plate member of a heat-conductivematerial brought into thermally close contact with the metal cap ofscaled block, said heat-collecting plate member being provided with aplurality of holes for allowing heated air current to be passedtherethrough so as to have the heat-collecting plate heatedsimultaneously from its member including a depending peripheral t'langein heat-conducting engagement with said metal cap so that theheat-collecting surface area of the unit will be enlarged.

1. A heat detection comprising a sealed block including a heatconductivemetal cap, a base member for holding said sealed block, a heat-sensitivebimetal element contained in said sealed block in such manner that itsconvex side surface at lower temperature will be thermally related tosaid metal cap of the sealed block, a contact assembly having a movablecontact and a fixed contact and contained in the sealed block togetherwith said bimetal element, said contact assembly being positionedadjacent said bimetal element so as to be operated upon selfdeformationof the bimetal in response to presented heat thereto, and aheat-collecting plate member of a heat-conductive material brought intothermally close contact with the metal cap of sealed block, saidheat-collecting plate member being formed in a diskshape and providedwith a plurality of bridge portions respectively separated from eachother by a plurality of vertical slits with respect to the plane of thedisk so as to be stepped alternately, so that heat-collecting surfacearea of the plate member will be increased and the plate will be heatedfrom its both front and reverse sides simultaneously.
 2. The heatdetection unit as set forth in claim 1, wherein said sealed blockcomprises said metal cap and an insulative receptacle member having aplurality of supporting columns, and said bimetal element is heldbetween said columns and metal cap, thereby possible dispersion ofcollected heat from the bimetal element will be restricted to beminimum.
 3. A heat detection unit comprising a sealed block including aheat-conductive metal cap, a base member for holding said sealed block,a heat-sensitive bimetal element contained in said sealed block in suchmanner that its convex side surface at lower temperatures will bethermally related to said metal cap of the sealed block, a contactassembly having a movable contact and a fixed contact and contained inthe sealed block together with said bimetal element, said contactassembly being positioned adjacent said bimetal element so as to beoperated upon self-deformation of the bimetal in response to presentedheat thereto, and a heat-collecting plate member of a heat-conductivematerial brought into thermally close contact with the metal cap ofsealed block, said heat-collecting plate member being provided with aplurality of holes for allowing heated air current to be passedtherethrough so as to have the heat-collecting plate heatedsimultaneously from its both surfaces, said heat-collecting plate memberalso being coupled with said metal cap of the sealed block in suchmanner that the horizontal plane of the plate member is spaced above thebottom surface of the cap, said plate member including a dependingperipheral flange in heat-conducting engagement with said metal cap sothat the heat-collecting surface area of the unit will be enlarged.